diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3dbe1360e..2e4bc5f74 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -212,8 +212,8 @@ add_library(gemmi_cpp
             src/align.cpp src/assembly.cpp src/calculate.cpp src/crd.cpp
             src/ddl.cpp src/eig3.cpp src/gz.cpp src/intensit.cpp src/json.cpp
             src/mmcif.cpp src/mmread_gz.cpp src/mtz.cpp src/mtz2cif.cpp
-            src/pdb.cpp src/polyheur.cpp src/read_cif.cpp src/resinfo.cpp
-            src/riding_h.cpp src/sprintf.cpp src/to_mmcif.cpp
+            src/pdb.cpp src/polyheur.cpp src/read_cif.cpp src/read_map.cpp
+            src/resinfo.cpp src/riding_h.cpp src/sprintf.cpp src/to_mmcif.cpp
             src/to_pdb.cpp src/monlib.cpp src/topo.cpp src/xds_ascii.cpp)
 add_library(gemmi::gemmi_cpp ALIAS gemmi_cpp)
 set_property(TARGET gemmi_cpp PROPERTY POSITION_INDEPENDENT_CODE ON)
diff --git a/fortran/gemmi.yaml b/fortran/gemmi.yaml
index 10c64993c..ddbfee60b 100644
--- a/fortran/gemmi.yaml
+++ b/fortran/gemmi.yaml
@@ -13,7 +13,6 @@ splicer_code:
   c:
     CXX_definitions: |
       // for read_ccp4_map() and read_ccp4_mask()
-      #define GEMMI_READ_MAP_IMPLEMENTATION
       #include "gemmi/read_map.hpp"
 
 declarations:
diff --git a/include/gemmi/read_map.hpp b/include/gemmi/read_map.hpp
index 979c6a30e..24c056f9e 100644
--- a/include/gemmi/read_map.hpp
+++ b/include/gemmi/read_map.hpp
@@ -2,48 +2,16 @@
 //
 // Functions for reading possibly gzipped CCP4 map files.
 // Trivial wrappers that can make compilation faster.
-//
-// The definitions are guarded by #ifdef *_IMPLEMENTATION.
-// If you use this header in your program, you need in exactly one file:
-// #define GEMMI_READ_MAP_IMPLEMENTATION
-// #include <gemmi/read_map.hpp>
 
-#ifndef GEMMI_GZREAD_MAP_HPP_
-#define GEMMI_GZREAD_MAP_HPP_
+#ifndef GEMMI_READ_MAP_HPP_
+#define GEMMI_READ_MAP_HPP_
 
 #include "ccp4.hpp"  // for Ccp4
 
 namespace gemmi {
 
-Ccp4<float> read_ccp4_map(const std::string& path, bool setup);
-Ccp4<int8_t> read_ccp4_mask(const std::string& path, bool setup);
-
-} // namespace gemmi
-
-#endif
-
-
-#ifdef GEMMI_READ_MAP_IMPLEMENTATION
-
-#include "gz.hpp"  // for MaybeGzipped
-
-namespace gemmi {
-
-Ccp4<float> read_ccp4_map(const std::string& path, bool setup) {
-  Ccp4<float> ccp4;
-  ccp4.read_ccp4(MaybeGzipped(path));
-  if (setup)
-    ccp4.setup(NAN);
-  return ccp4;
-}
-
-Ccp4<int8_t> read_ccp4_mask(const std::string& path, bool setup) {
-  Ccp4<int8_t> ccp4;
-  ccp4.read_ccp4(MaybeGzipped(path));
-  if (setup)
-    ccp4.setup(-1);
-  return ccp4;
-}
+GEMMI_DLL Ccp4<float> read_ccp4_map(const std::string& path, bool setup);
+GEMMI_DLL Ccp4<int8_t> read_ccp4_mask(const std::string& path, bool setup);
 
 } // namespace gemmi
 
diff --git a/python/ccp4.cpp b/python/ccp4.cpp
index 3f74251a4..9aa352580 100644
--- a/python/ccp4.cpp
+++ b/python/ccp4.cpp
@@ -1,12 +1,11 @@
 // Copyright 2018 Global Phasing Ltd.
 
 #include "gemmi/ccp4.hpp"
+#include "gemmi/util.hpp"  // for cat
+#include "gemmi/read_map.hpp"  // for read_ccp4_map, read_ccp4_mask
 #include "common.h"
 #include <pybind11/stl.h>
 
-#define GEMMI_READ_MAP_IMPLEMENTATION
-#include "gemmi/read_map.hpp"  // defines read_ccp4_map, read_ccp4_mask
-
 namespace py = pybind11;
 using namespace gemmi;
 
diff --git a/src/read_map.cpp b/src/read_map.cpp
new file mode 100644
index 000000000..0278650c5
--- /dev/null
+++ b/src/read_map.cpp
@@ -0,0 +1,24 @@
+// Copyright 2021 Global Phasing Ltd.
+
+#include "gemmi/read_map.hpp"
+#include "gemmi/gz.hpp"  // for MaybeGzipped
+
+namespace gemmi {
+
+Ccp4<float> read_ccp4_map(const std::string& path, bool setup) {
+  Ccp4<float> ccp4;
+  ccp4.read_ccp4(MaybeGzipped(path));
+  if (setup)
+    ccp4.setup(NAN);
+  return ccp4;
+}
+
+Ccp4<int8_t> read_ccp4_mask(const std::string& path, bool setup) {
+  Ccp4<int8_t> ccp4;
+  ccp4.read_ccp4(MaybeGzipped(path));
+  if (setup)
+    ccp4.setup(-1);
+  return ccp4;
+}
+
+} // namespace gemmi